Drill bit with self-renewing teeth



Jan. 3, 1967 D. M. WILLIS DRILL BIT WITH SELF-RENEWING TEETH 2 Sheets-$heet 1 Filed June 10, 1964 jmT Jan. 3, 1967 D. M. WILLIS DRILL BIT WITH SELFRENEWING TEETH Filed June 10, 1964 Fig. 6

Donald M. Willis United States Patent 3,295,617 DRILL BET WETH SELF-RENEWING TEETH Donald M. Willis, Monroe, La, assignor to imagineering, Inc., a corporation of Louisiana Filed June 10, 1964, Ser. No. 373,911 9 Claims. (Cl. 175--379) This invention comprises a novel and useful drill bit with self-renewing teeth and more particularly pertains to a drill bit specifically adapted for use in drilling deep wells such as petroleum or gas wells and wherein the unavoidable wear to which the teeth of the bit are subjected is utilized to successively expose and make available fresh cutting surfaces and teeth incorporated into the structure of the bit.

In the drilling of deep wells by the rotary drilling method, there is an unavoidable and often rapid wear and deterioration of the teeth and cutting surfaces of the drill bit as a result of the abrasive action of the formation through which the bit is drilling which at more or less short intervals of time necessitates the removal of the drilling string from the well bore in order that the no longer effective bit may be replaced. In the drilling of deep wells, the actual time delay in the drilling operation as well as the act of withdrawing the drilling string from the well bore and then reinserting the drilling string into the well bore is extremely undesirable. According- 1y, it is the primary purpose of this invention to provide a drill bit which shall have a very much greater period of useful life than conventional bits in order to reduce to a minimum the disadvantages of ceasing the drilling operation and withdrawing the drill string from and reinserting it into a well bore.

It is a further purpose of the invention to provide an improved drill bit which shall be so constructed that continuing wear of the bottom surface of the bit by the drilling operation will successively uncover and expose fresh drilling surfaces and a new drilling fluid circulating system of passages over such renewed drilling surfaces in order to thereby restore the bit to its maximum efficiency.

A further purpose of the invention is to provide a drill bit in accordance with the foregoing objects wherein there is cast or otherwise fabricated in the body of the bit a multitude of cavities or cells together with a plurality of radially extending voids, with the cavities and voids being disposed in directly spaced horizontal layers ex tending outwardly from an axial bore in the center of the bit.

A further object of the invention is to provide a drill bit in conformity with the above set forth objects wherein the voids and cavities of one layer are respectively rotationally displaced about the vertical axis of the bit in order to thereby overlap the corresponding voids and cavities of the adjacent layer.

Still another purpose of the invention is to provide a drill bit in accordance with the preceding objects consisting of a generally cylindrical shaped body having an axial vertical bore therethrough for the passage of drilling fluid together with a plurality of horizontally extending passages or voids radiating outwardly from and communicatin g with this axial bore for the passage of drilling fluid therefrom and with the communication of the passages being blocked by a thin walled sleeve fixed in the bore and sufficiently frangible and rupturable in nature to permit its exposed lower edge being rupture, eroded or Worn away by the action of the drilling fluid to establish communication between the axial bore and the lowermost exposed or uncovered layer of radial voids.

A further object of the invention is to provide a drill bit in conformity with the above set forth objects whereice by the attrition and wearing away of successive bottom layers of the bit will uncover successive layers of drill fluid circulating radial voids and cavities or cells whereby to provide both renewed cutting edges and teeth with provision for the conducting of the drilling fluid directly to and across the renewed teeth.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a view in vertical central section of a portion of a well bore showing a drilling string therein in which is incorporated the novel drill bit of this invention;

FIGURE 2 is a detail view in horizontal section taken upon an enlarged scale substantially upon the plane indicated by the section line 2-2 in FIGURE 1 and showing partly in plan and partly in horizontal section the upper portion of the drill bit of this invention;

FIGURE 3 is a horizontal sectional detail view taken upon an enlarged scale substantially upon a plane indicated by the section line 33 of FIGURE 2 and showing the bottom or cutting face of the drill bit of this invention;

FIGURE 4 is a view in vertical central section taken upon an enlarged scale substantially upon the plane indicated by the section line 44 of FIGURE 1 and showing the internal construction of the drill bit and its radial void system with a part of the central sleeve of the bit being shown in elevation and with the flow of the drilling fluid being indicated by arrows therein;

FIGURE 5 is a fragmentary view of the lower portion of FIGURE 4 but showing the bit in actual operation after the flow of drilling fluid has slotted, ruptured or worn away the lower edge of the wall of the central sleeve and opened to flow of drilling fluid into the lowermost set of exposed radial voids of the bit;

FIGURES 6 and 7 are horizontal sectional views taken upon enlarged scales substantially upon the planes indicated by the section lines 6-6 and 7-7 of FIGURE 4; and,

FIGURE 8 is a perspective view of the drill bit.

The self-renewing drill bit in accordance with this invention is intended and specifically designed to wear out evenly and progressively from the bottom or cutting face thereof upwardly towards the shank and to progressively expose newly formed sharp cutting edges or teeth on the bottom of the bit. The bit is preferably of a suitable steel alloy although in some instances it may be constructed of a durable plastic or other materials including conglomerates or mixtures of materials.

Referring now first to FIGURE 1 it will be observed that the numeral lit designates generally the improved self-renewing drill bit in accordance with this invention which is shown as connected to, communicating with and supported by the lower end of the drilling string 12 operated by any suitable means, not shown, in accordance with rotary drilling methods, in a well bore 14-. The drill bit llil includes a preferably homogeneous and one-pies body 16 of suitable material of a generally cylindrical configuration which as shown in FIGURE 8 has recessed planar or rounded sides or faces 18 between which lie relatively narrow corner faces it to thereby provide adequate clearance between the bit and the wall of the well bore 14 to permit the passage of drilling fiuid upwardly of the well annulus from the cutting region of the bit to the surface.

While the bit may be fabricated in various ways, one satisfactory construction is shown in FIGURE 4 wherein a pin 22 is welded as at 24 or otherwise secured to the top surface of the body 16 of the bit to provide a connection to the box 26 on the lower end of the drilling string 12. It will be noted that the bit has an axial bore 28 extending entirely therethrough so that the interior of the drilling string communicates with the interior of the bit in order that drilling fluid, circulating in the usual manner, may pass downwardly through the drilling string and then across the lower face of the bit and then return with the bit cuttings up the well annulus to the surface.

Press fitted or otherwise fixedly secured to the axial bore 28 is a sleeve 30 whose lower end opens at the bottom surface 32, see FIGURE 3, of the bit and whose upper end projects above the top surface 34 thereof and into a counterbore 35 disposed in the pin 22. The sleeve conducts the drilling fluid from the drilling string downwardly through the bit and discharges it as indicated by the arrows in FIGURE 4 below the bottom or lower face 32 of the bit radially outwardly from the center, and then between the flats 18 and the well bore 14- to the surface carrying with it the drilling cuttings and also serving to cool and lubricate and cleanse the cutting elements or surfaces of the drill bit.

In accordance with this invention the bit is provided with a multitude of voids and/or cavities. Thus, there are provided vertically spaced horizontally extending radial passages or voids 33 whose inner ends communicate with the axial bore 2t) and whose outer ends have discharge openings upon the exterior surface of the bit. As will be apparent from FIGURES 3, 6 and 7, the radial voids or passages 38 are separated by walls 42. Preferably, as will be noted from FIGURES 3, 6 and 7, the radially extending voids and passages 38 are disposed in the edge or corner faces 20. Intersecting these passages or voids are a plurality of other passages or cavities indicated at 43 and which have discharge openings 44 opening upon the faces 13 of the bit.

The radially extending voids 38 and the cavities or cells 42 thus honeycomb the structure of the bit and are disposed in vertically spaced horizontally extending layers. The radial passages 38 of one layer and the cavities 43 of that layer are rotationally displaced about the vertical axis of the bit with respect to the adjacent layers so as to cause the cavities and voids or passages to overlap each other as will be readily apparent from FIGURE 8 and from a comparison of FIGURES 6 and 7. The overlapping of the cavities and voids is both in a circumferentially extending direction and also in a vertical direction.

It will be observed that the cavities 42 are separated by walls or partitions as and each of the voids and cavities has a bottom wall indicated at 4-8 and 5% respectively.

The operation of the bit structure is as follows. In its original condition before use, the bit structure is as shown in FIGURE 4 with the lowermost layer of voids and cavities being without a bottom wall. As the drilling operation progresses, the cutting edges formed by the bottomless lower edges of the partitions or walls 52 and 46 of the radial voids 33 and the cavities 43 constitute drilling teeth during the. rotation of the drill bit by the drill string. The flow of drilling fluid down through the drilling string and through the sleeve 3% following the direction of the arrows emerges from the open lower end of the sleeve 30 and then moves radially outwardly across the face of the bit, following the radial voids and the cavities 38 and 43. Since the bottom wall of the overlying cavity or void 48 or 50 is spaced some distance above the open lower edge of the sleeve 39, the drilling fluid under the tremendous pressure applied thereto after passing beneath the lower edge of the sleeve 30, will form a vortex or eddy and a region of great turbulence adjacent the lower edge as shown by the arrows in FIGURE 4. Owing to the pressure difference on the opposite sides of the thin lower edge of the sleeve, this action of the drilling fluid will rapidly erode, wear away or rupture the relatively thin and frangible material of the sleeve and thus form slots as at 52 therein, see FIG- URE 5. These slots will extend the full vertical height of the sleeve up to the next bottom wall 48 or 50 superposed thereabove. Thus, the exposed uncovered lower edges of the partitions or side walls of the radial voids and cavities will constitute drilling teeth and the drilling fluid will circulate therealong by virtue of the channels 38 and 43 thus enabling the drill to function at its maximum efliciency. As the drill wears, and the bottom cutting surface thereof moves slowly upwardly due to this wearing away of the lower portion of the bit, the lowermost layer of voids and cavities will be worn away exposing the superposed layer. As the bottom wall is allowed to wear away, the side walls of these voids and cavities provide fresh cutting surfaces thereby renewing and restoring the efliciency of the drilling bit. At the same time, the drilling fluid will again be permitted to have great turbulence as it passes from the interior of the sleeve 30 and upwardly beneath the next bottom wall thereabove, again slotting, eroding or rupturing the sleeve to provide the drilling fluid slots 52 therein.

It should be noted that this slotting action will be stopped by the wall 48 thereabove and as the sleeve and the bottom surface of the bit wear upwardly to this next bottom wall, there will be a streamline or laminar flow of the fluid which will cause the slots to terminate at the bottom wall of the next layer of radial voids and cavities thereabove.

Thus, in addition to the renewing of the cutting surface of the bit by wear, there results a further restoration of the drilling fluid circulating system for the particular cutting surfaces which are exposed.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

I. A self-renewing drill bit comprising a vertically elongated body having a bottom surface constituting a cutting face and an axial bore through said body for the passage of drilling fluid to said cutting face, said body being vesicular and having a plurality of vertically spaced layers of horizontally extending voids therein, each void being defined by side walls and a bottom wall whereby when said bottom walls are worn away, the lower edges of said side walls will constitute new cutting elements for said body bottom surface.

2. The combination of claim 1 wherein adjacent layers are rotationally displaced about the axis of said bore and their voids overlap each other both axially and rotationally.

3. The combination of claim 1 wherein said body is generally cylindrical with flat sides and flattened corners therebetween, said voids extending radially through said corners.

4. The combination of claim 3 including cavities in said body in each layer extending from said voids to said flat sides. a

5. The combination of claim 1 wherein said voids have their inner ends opening into said axial bore.

6. The combination of claim 5 including an open ended sleeve in said bore closing communication between said voids and said bore.

7. The combination of claim 6 wherein said sleeve is of a relatively readily rupturable and erodible material whereby the lower end thereof exposed to the open bottomed voids of the lowermost layer will be slotted by the flow of drilling fluid thereacross estabishing a direct flow of drilling fluid across and through the exposed set of cutting elements.

3. The combination of claim 7 including cavities in said body in each layer extending from said voids to said flat sides, said drilling fluid flowing from said voids to said cavities of said lowermost layer.

9. The combination of claim 8 wherein some of said cavities communicate with said axial bore.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 6/1936 Germany.

CHARLES E. OCONNELL, Primary Examiner.

N. C. BYERS, Assistant Examiner. 

1. A SELF-RENEWING DRILL BIT COMPRISING A VERTICALLY ELONGATED BODY HAVING A BOTTOM SURFACE CONSTITUTING A CUTTING FACE AND AN AXIAL BORE THROUGH SAID BODY FOR THE PASSAGE OF DRILLING FLUID TO SAID CUTTING FACE, SAID BODY BEING VESICULAR AND HAVING A PLURALITY OF VERTICALLY SPACED LAYERS OF HORIZONTALLY EXTENDING VOIDS THEREIN, EACH VOID BEING DEFINED BY SIDE WALLS AND A BOTTOM WALL WHEREBY WHEN SAID BOTTOM WALLS ARE WORN AWAY, THE LOWER EDGES OF 